Atholus famulus ( Lewis, 1892 )

Cruz, Ian Niel dela, Hartini, Sri, Dwibadra, Dhian & Ôhara, Masahiro, 2024, Contribution to the Knowledge of the Genus Atholus (Coleoptera: Histeridae: Histerinae: Histerini) from the Indonesian Archipelago, Species Diversity 29 (1), pp. 119-139 : 123-127

Atholus famulus ( Lewis, 1892)

( Figs 1E , 2A–F , 3A–H , 4A–F , 5A–C , 12 )

Hister famulus Lewis, 1892: 346 (type locality: Sumatra).

Atholus famulus : Lewis 1906: 402; Mazur 1984: 214; Mazur 1997: 131; Mazur 2011: 105 (catalogued).

Hister (Atholus) famulus : Bickhardt 1910: 54; Bickhardt 1917: 194 (catalogued); Desbordes 1917: 319 (keyed).

Hister sp. : Aoki and Harada 1982: 346, 369.

Specimens examined. OneJ and 1♀. Borneo Island: 1 km north of Camp Pemantus, 73 km north of Sotek , alt . 310 m, natural forest, East Kalimantan, 23 December 1980 ,

J. Aoki leg . (Bo-14A) [IC-22-in03, IC-22-in04]; (1J and 1♀ SEHU) ( Aoki and Harada 1982) .

Diagnosis. Atholus famulus is remarkable for its strongly dilated protibia, which is almost trilobed-like in structure. The male aedeagus is also quite peculiar having a small extended membrane on its anterior portion, but inconspicuous.

Re-description. Male, female. Body length: PEL: 3.00, 3.25 mm; APW: 1.25, 1.25 mm; PPW: 2.44, 2.60 mm; EL: 1.70, 1.70 mm; EW: 2.75, 2.80 mm. Body ( Figs 1E , 2A–C ) oval and convex; color from dark rufous to black; tibia, antenna, mouthparts and apical elytral margin rufous.

Head. Apical margin of clypeus entire, anterolateral margin feebly sinuous laterally; frontal stria ( Fig. 2D ) round and deeply impressed; disk covered sparsely with fine punctures, separated by five times their diameter, with alutaceous ground sculpture; occipital fovea absent; eyes well-visible dorsally; labrum strigate on surface, slightly oblong, labral fringe absent; mandible rather small, outer margin rounded and curved inwardly, mandibular apex acutely pointed.

Pronotum. Marginal stria laterally complete, weak on anterolateral angle; lateral pronotal stria ( Fig. 2E ) short and deeply impressed, the lateral stria rather distant from the margin, its basal end abbreviated to basal 3rd, the apical end interrupted; anterior pronotal stria present, feebly connected to marginal stria; disk with sparse microscopic punctures, clothed with alutaceous microsculpture; area behind apical angle bare; posterior margin with very sparse, inconspicuous punctures; ante-scutellar region with short puncture.

Elytra. Anterior margin with row of short, longitudinal striae present on apical area around antero-scutellum; epipleural fossette bare; epipleural marginal stria absent; elytral marginal stria complete; external subhumeral ( Fig. 3B ) stria present medio-basally; internal subhumeral stria absent; oblique stria lightly impressed on basal third; dorsal striae ( Fig. 3A ) 1–4 complete, dorsal stria 5 present on apical third, sutural stria moderately longer, reaching beyond middle, abbreviated on basal third; disk surface similar to pronotum with alutaceous microsculpture.

Propygidium and pygidium. Propygidium ( Fig. 3E, F ) finely and loosely punctate, few shallow and coarse punctures scattered on basal area; pygidial ( Fig. 3E ) punctations similar to that of propygidium, becoming smooth on apex.

Prosternum. Prosternal lobe with moderately truncate and short anterior margin ( Fig. 3C ), medio-apical end ascending, marginal stria absent, striae present on basolateral ends brief and carinated; lobe with setiferous coarse punctures on anterolateral region, interspace among these punctures with sparse fine punctations, prosternal suture inconspicuous; prosternal process clothed with sparse fine punctures, the lateral sides descending; descending lateral stria moderately impressed and carinate; lateral disk with very few fine punctations; basal half of process narrow, posterior margin of basal lobe strongly emarginated.

Meso- and metaventrite. Anterior margin arcuate outwards ( Fig. 3D ), marginal stria complete, moderately impressed, stria behind anterolateral angle present; disk sparsely clothed with fine punctures on basal margin, which are separated by three to five times their diameter; meso-metaventral suture lightly impressed, complete and lightly angulated at middle; metaventral lateral ( Fig. 3D ) stria deeply impressed and carinated, extending obliquely and posteriorly, united with oblique stria which inwardly extends from basal third of metaventro-metepisternal suture; post-mesocoxal stria extending posteriorly and strongly curved along the posterior margin of mesocoxa, almost attaining the metaventro-mesepimeral suture; metaventrite with punctations of intercoxal disk similar to those of the apex of mesoventral plate; row of coarse punctures sometimes present along inside of basal portion of lateral stria; longitudinal suture lightly impressed; lateral disk of metaventrite densely covered with setiferous, large, round, shallow punctures; interspaces among the large punctures with sparse, fine to coarse punctations; mesepimeron and metepimeron covered with densely setiferous, large punctures, interspaces among the punctures with few, fine to coarse punctations; metepisternum with sparse punctures on apical half; first abdominal sternite with punctation of intercoxal disk of similar to that of metaventrite; surface of lateral disk similar to mesepimeron and metepimeron; lateral stria deeply impressed, slightly carinate and complete.

Legs. Anterior surface of protibia ( Fig. 3G ) strongly dilated, becoming broader towards apical region, appearing trilobed; surface clothed with few, fine ocelloid punctures; the median area with weak strigate sculpture; outer lateral margin with three weak teeth topped with small denticles; anterior protibial stria complete and moderately impressed; inner marginal stria present almost on basal half; posterior surface ( Fig. 3H ) covered with sparse, fine punctures, the outer surface of ground sculpture strigate, the outer region slightly descending; number of denticles on both outer lateral margin and apical margin combined 9, one on inner apical angle; spur moderately long, almost half the length of protarsus; median posterior stria complete and moderately impressed; inner posterior stria lightly impressed with row of few sclerotized setae. Protarsal groove shallow. Protarsus with two spine-like tarsal denticles present; another one or two more distant, located at inner anterior angle; profemur sparsely clothed with fine punctations, the surface with strigate ground sculpture; marginal and anterior striae absent; femoral stria complete; posterior margin with few, large punctations, row of setae present on apical end.

Male genitalia. Aedeagus ( Fig. 4A, B ) slightly stout, apically curved ventrad; parameres shorter, about half the length of phallobase; median lobe sclerotized; the anterior portion with extended membrane covered with sparse, short setae; eighth tergite ( Fig. 4E, F ) entire, with longitudinal fold on both lateral sides; ninth tergite ( Fig. 4C, D ) with lateral folds; tenth tergite simple; spiculum gastrale almost as same length as ninth tergite, bifurcate on apical fifth.

Female genitalia. Anterior portion of valvifers ( Fig. 5A, B ) paddle-shaped; gonocoxite ( Fig. 5C ) slightly elongate, almost as twice as broad, shovel-like; inner and outer surfaces differentiated; inner face moderately separated outer face by elevated lateral ridge; sclerotized setae on apical quarter of outer face short and slightly dense; inner face with short and sparse setae; apex of gonocoxite with two teeth; gonostyli present, articulated; spermathecae multiple, consisting of four sacs; sacs gradually enlarged and elongate, not sclerotized.

Distribution. Indonesia: Greater Sunda (Sumatra and Borneo Islands) ( Fig. 12 ).

Remark. This species is relatively small, about the same body size of A. coelestis .

Figures

Fig. 1. Some Indonesian Atholus, dorsal habitus. A, Atholus bifrons (Marseul, 1854), IC-22-in01; B, A. philippinensis (Marseul, 1854), IC- 22-in06; C, A. coelestis (Marseul, 1857), IC-22-in02; D, A. myrmidon (Marseul, 1861), IC-22-in05; E, A. famulus (Lewis, 1892), IC-22-in03; F, A. singalanus (Marseul, 1880), IC-22-in07; G, A. torquatus (Marseul, 1854), IC-22-in08. Scale bar: 1.00mm.

Fig. 2. Atholus famulus (Lewis, 1892), SEM micrographs, IC-22-in03. A, Habitus, dorsal view; B, ditto, ventral view; C, ditto, oblique view; D, head, dorsal view; E, pronotum; F, mouthparts, ventral view.

Fig. 3. Atholus famulus (Lewis, 1892), SEM micrographs, IC-22-in03. A, Elytra, dorsal view; B, ditto, oblique view; C, prosternal process; D, meso- and metaventrite; E, propygidium and pygidium; F, propygidium (punctation); G, protibia, dorsal view; H, ditto, ventral view.

Fig. 4. Atholus famulus (Lewis, 1892), male genitalia, IC-22-in03. A, Aedeagus, dorsal view; B, ditto, lateral view; C, ninth and tenth tergites, and spiculum gastrale, dorsal view; D, ditto, lateral view; E, eighth tergite and sternite, dorsal view; F, ditto, lateral view. Scale bar: 0.20mm.

Fig. 5. Atholus famulus (Lewis, 1892), female genitalia, IC-22-in04. A, Dorsal view; B, lateral view; C, gonocoxite, dorsolateral view. Scale bars: 0.20mm.

Fig. 12. Map showing the occurrence of some species of Atholus from the Indonesian archipelago and its extra-limital distribution in the Oriental Region.